Britain should set an example to the world by reversing its steeply-rising population growth and allowing no more people into the country than leave, the Government's chief "green" adviser has said.

Jonathon Porritt, chairman of the Sustainable Development Commission, said it was entirely possible to be "very progressive" on immigration while still having a policy of "zero net immigration" and no further population growth.

Mr Porritt told an audience at the Cheltenham Science Festival, he would like to see Britain's population on a declining trend, instead of increasing to 65 million in ten years and to 70 million by 2031.

Population growth was a popular topic for environmentalists back in the 1970s. Then leftists decided that population growth was racists since almost all population growth was in non-white populations. But the environmental problems with population growth have become so large and noticeable and set to get so much worse that environmentalists are being forced to confront it. I expect population reduction to make a come-back as as a "green" issue. Humans are going to wreck the world if we do not control our numbers.